How to search for 'metakey' (VirtueMart 2.6.22)?

[REandH]

Hello
In file:
      administrator\components\com_virtuemart\helpers\shopfunctions.php

Couldn't add in admin panel the field 'metakey' (fields from products) -- The result is an empty category page of products

There is a developer comment
      // this fields leads to trouble, because we have this fields in product, category and manufacturer,
      // they are anyway making not a lot sense for orderby or search.

Please tell me how to configure search 'metakey' products from table  virtuemart_products_**_**  ?